The present invention relates to a chain saw bar tightener. More particularly, the invention relates to a chain saw bar tightener for a chain saw having a chain bar of substantially elongated plate-like configuration having elongated top and bottom edges with a groove formed therein for guiding a chain. The chain bar has front and back edges with a groove for guiding the chain and a slot extending into the chain bar substantially parallel to the top and bottom edges from the back edge. The chain saw also has a housing casting.
Objects of the invention are to provide a chain saw bar tightener of simple structure, which is inexpensive in manufacture, installed with facility and convenience on new and existing chain saws, and functions efficiently, effectively and reliably to selectively tighten and loosen the chain of a chain saw without the need for dismantling the saw.